As is well known, so-called horizontal axis wind turbines are used broadly in wind-powered electric power generating equipment. Typically the horizontal axis wind turbine is structured comprising a rotor to which blades are attached radially from a hub, a nacelle wherein a rotor is supported rotatably through a main axis that extends in essentially the horizontal direction, to which the hub is attached, and a tower that supports the nacelle rotatably in the yaw direction, and which is disposed in essentially the vertical direction.
The nacelle contains heat-producing equipment requiring cooling, such as a step-up gear and an electric generator that are connected to the main axis. Because of this, the nacelle is provided with an air inlet aperture and an exhaust aperture within the structure to perform air-cooling on this equipment. In this case, the air that has absorbed heat from the heat-producing equipment is guided to the exhaust aperture and expelled to the outside of the nacelle, or a method is used wherein a radiator is equipped above the nacelle.
Patent documents 1 through 3 disclose horizontal axis wind turbines having air-cooled structures.
Patent document 1 (Japanese Unexamined Patent Application Publication S58-65977) discloses a horizontal axis wind turbine provided with an air inlet aperture on the bottom surface of the nacelle, and an exhaust aperture that is formed in the shape of a V, facing towards the outside, in the front surface end portion of the nacelle.
Patent document 2 (Japanese Unexamined Patent Application Publication 2001-526357) discloses a horizontal axis wind turbine wherein the electric generator is cooled through the provision of an air inlet aperture in the tower, and a gap in front of (on the blade side of) the electric generator.
On the other hand, patent document 3 (Japanese Unexamined Patent Application Publication 2002-13467) discloses a horizontal axis wind turbine wherein a fin is provided on the outside of the blade frame on the rear side.
In addition to the documents described above, in conventional horizontal axis wind turbines structures can be seen wherein exhaust apertures are open on the back end and side surfaces of the nacelle.
In conventional horizontal axis wind turbines, including those described in patent document 1 through 3, the positions of the air inlet aperture and of the exhaust aperture are fixed at a specific position relative to the nacelle.
In the normal horizontal axis wind turbine, yaw control is performed to control so as to face upwind, but it is necessary for the design to take into consideration times when there is a rapid change in the wind direction that cannot be followed through yaw control, or when there is a power stoppage or when the yaw system malfunctions, and to take into consideration storm winds coming from all directions.
When considering storm winds coming from all directions, in the case of the exhaust aperture being at a fixed position relative to the conventional nacelle, there will be cases when the storm wind is received in the exhaust aperture, and in such cases there will be an increased pressure within the exhaust aperture, and by extension, within the nacelle, which bears the risk of damaging or deforming the exhaust path, the surrounding structure, the equipment within the nacelle, and so forth. Conventional horizontal axis wind turbines are designed to protect against this, requiring high strengths, which is a factor that increases costs.
The present invention is a result of contemplation on the problem areas, described above, in the conventional technology, and the object thereof is to provide a horizontal axis wind turbine, provided with an exhaust aperture for exhausting the air within the nacelle, wherein the exhaust aperture can be faced away from the storm wind, even if there are storm winds from all directions relative to the nacelle.